1. Field of Invention
The invention relates to an antenna matching circuit control device and, more particularly, to an antenna matching circuit control device applied to a wireless communication device.
2. Related Art
In consideration of consumers' health, every country limits an electromagnetic wave specific absorption rate (SAR, Specific absorption rate, is a measurement at which energy is absorbed by the body when exposed to a radio frequency (RF) electromagnetic field) of electromagnetic wave-emitting wireless communication device (such as a mobile phone or a tablet PC) in a safe range, so as to avoid harm from massive electromagnetic waves. The higher the SAR value is, the more serious potential harm to human body could be.
If the wireless communication device does not pass the electromagnetic wave SAR test or relevant safety inspection, it will not be legally sold or imported. As the wireless communication device becomes thinner, it is more difficult to reduce the electromagnetic wave SAR of which to meet the safety standard.
Moreover, when an object such as a human body approaches or contacts a casing of the wireless communication device, a coupling effect is generated and results in frequency drift of the antenna, which is called a body effect. The frequency drift of the antenna reduces a radiation efficiency of the antenna and affects the wireless communication quality. Consequently, to produce wireless communication devices, the electromagnetic wave SAR and the body effect on the communication quality should take into consideration.